Gag
|
A device attached to
a safety or safety relief valve that prevents it from opening at the set
pressure. |
Galling
|
A form of wear
in which surfaces experience seizing or tearing; e.g., of a gear or bearing
surface. |
| Gallon |
A unit of volume.
A US gallon has 231 cubic inches or 3,785 liters. |
Gas
|
One of the three basic phases of matter. While air is a gas, in
pneumatics the term "gas" normally is applied to gases other than air.
Otherwise, it is considered a fluid (as hydrogen or air) that tends to
expand indefinitely. |
Gas bearings
|
Load carrying machine elements permitting some degree of
motion in which the lubricant is air or some other gas. |
Gas Bypass
|
A portion of
the discharge gas is redirected through a heat exchanger and then expanded
back to suction pressure, where it is mixed with normal suction gas stream
and commonly used to compensate for process flow demands. |
Gas Compressor
|
A machine
that compresses gases. Divided into two groups; process gas compressors and
oil and gas field compressors. |
Gas Drying
|
The drying of
compressed gases other than air. Equipment size, choice of materials and
other specifications may be decidedly different for drying gases other than
air because of the specific properties of the gases. Properties include
specific gravity, specific heat, viscosity, thermal conductivity, explosive
characteristics, toxicity, corrosion and others. |
Gas Laws
|
The behavior of perfect gases, or mixtures thereof, that follow a set of laws;
e.g.,
Boyle' law, Charle's law, Amonton's law, Dalton's law, Amagat's law,
Avogadro's law, Poisson's law, etc.. |
Gate Valve
|
A type of valve in which the closing element (the gate) is a disc that moves
across the stream in a groove or slot for support against pressure. A gate
valve has relatively large full ports and a straight line flow pattern. The
design has very
little pressure drop; however, it is subject to leakage if the sealing surfaces are
scored or marred, or if debris becomes lodged in the grove. |
| Gauge |
An instrument for
measuring, testing, or registering. |
Gauge Pressure
|
The pressure determined by most instruments and gauges,
usually expressed in psig. Barometric pressure must be considered to obtain
true or absolute pressure. |
| Glycol Dehydration |
A
method of drying natural gas. |
Governor
|
A motor
controller that regulates the air flow through an end plate into the motor
to control the speed and power. A speed regulation device built into or
attached externally. |
| GPM |
A measurement of
flow in gallons per minute. |
| Grade "D" Breathable Compressed Air |
ANSI Specification for a Compressed Air Supply Source that meets OSHA
specification # 1910.134(i)(1)(ii)requirements for breathing air. |
Gravimetric Efficiency
|
The efficiency of the filter in removing some
portion of a specified test contaminant under a specific set of laboratory
conditions. It determines the mass of the contaminant the filter removes
from a known sample introduced to the filter. |
| Guide |
The portion of a
valve used to guide the disc. |
Guide Vane
|
A stationary element that may be adjustable and which directs
the flowing medium approaching the inlet of an impeller. |
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